Traditional slot machines have a plurality of rotating mechanical reels, which rotate and then stop to show symbols on one or more paylines drawn across the reels. Players wager coins or credits on one or more of these paylines and are paid for certain combinations of symbols on a payline for which a wager has been placed. Video slot machines typically show the same type of reel configuration on a video display. Video slot machines typically offer the same types of features as their mechanical counterparts, and often add in a bonus game that occurs when a game results in a particular symbol combination. In certain slot machines there may be combinations of symbols that pay the player that are not necessarily confined to paylines, such as “scatter” pays which may be awarded when certain symbols appear in any visible position on certain reels. There have been games that do not have any paylines, but rather, pay for symbol combinations wherever they occur (e.g. “Spin Keno”, U.S. Ser. No. 10/090,685).
There have been games where, after certain initial results, a random event modifies this result. This has been seen in games with a “respin” feature, such as IGT's “Double Spin Double Diamond”. In that game, at the end of each initial game spin, if changing the third reel could possibly improve the result without the risk of a lesser result, then the third reel is respun by selecting an additional random number.
There have been games where the final result is modified after the spin in a non-random manner. For example, this has been done using a “nudge” feature (e.g. “Double Diamond Deluxe” by IGT) where certain symbols will rise to the payline when they appear below the payline, or other symbols will fall to the payline when they appear above the payline. There have been other games where the player is allowed to “nudge” certain reels after the result to attempt to modify the original result to a better result.
There is a multi-line video slot machine (“Penguin Pays” by Aristocrat) where, after a certain symbol combination is achieved, then a certain symbol is sequentially substituted for each of the fifteen symbols. After each substitution, all paylines are evaluated and the player is paid for all winners in each evaluation.